Breadboards are used to test circuits. Wires and
components are simply pushed into the holes to form a completed circuit
and power can be applied. One of the main advantages of using a
breadboard is that the components are not soldered and if they are
positioned incorrectly they can be moved easily to a new position on the
board.
On the breadboard (diagram 1) seen
opposite, letters are used to identify vertical columns and numbers to
identify horizontal rows.

The red lines on diagram 2 show how some
vertical columns and horizontal rows are internally connected. When
power is applied to the breadboard current flows along these internal
connections.

Diagram 3 shows how a
380 ohm resistor and an LED are setup on a breadboard. When a 9 volt
battery is attached the LED lights. Try replacing the resistor with a
higher value such as a 680 ohm resistor. The resistance will be greater
and the LED should shine less bright.